The olive tree and other members of the family Oleaceae have been documented as a source of medicinal substances since biblical times. Many researchers have studied the cocktail of phytogenic substances produced by the olive and other members of this family. One compound that has received particular attention from the research community is a glucoside known as oleuropein. A number of scientific studies have shown this compound to have certain anti-viral, anti-fungal, and anti-bacterial properties (Koutsoumanis; et al., 1998; Aziz, et al., 1998; Tranter, et al., 1993; Tassou, et al., 1995), anti-oxidant properties (de la Puerta, et al., 1999; Visiola, 1998a), and anti-inflammatory properties (Visioli, et al., 1998b). Interest in natural anti-oxidants is increasing because of the growing body of evidence indicating the involvement of oxygen-derived free radicals in several pathologic processes, such as cancer and atherosclerosis.
Not surprisingly, the market for oleuropein is quite substantial. Dietary supplements containing oleuropein are readily obtainable via mail-order catalogs and the internet. Currently, most of the oleuropein commercially available to consumers is derived from olive leaves. To date, the fruit of the olive plant, which is rich in oleuropein, has largely been ignored as a source of oleuropein due to certain problems associated with the production of olive oil, discussed below.
Conventionally, olive oil production involves crushing olives, including the pits, to produce a thick paste. During this procedure, the crushed olives are continuously washed with water, a process known as “malaxation.” The paste is then mechanically pressed to squeeze out the oil content. In addition to providing olive oil, the pressing also squeezes out the paste's water content. Such washing and pressing steps yield a considerable amount of water, referred to as “vegetation water.”
Both the pit and the pulp of olives are rich in water-soluble, phenolic compounds. Such compounds are extracted from olives during malaxation, according to their partition coefficients, and end up in the vegetation water. This explains why various polyphenolic compounds, such as oleuropein and its derivatives, produced in olive pulp, can be found in abundance in vegetation waters. Similarly, a number of monophenolic compounds, such as tyrosol and its derivatives, produced in olive pits, are also abundant in vegetation waters.
Oleuropein and its derivatives are readily degraded into breakdown products (e.g., upon exposure to air/oxygen, certain enzymes or bacteria) that are substantially non-polluting and non-toxic. Tyrosol and its derivatives, on the other hand, are substantially resistant to air/oxygen, bacterial and enzymatic degradation and are of a highly polluting nature. Unfortunately, current technology does not permit the isolation of oleuropein and its derivatives from such highly polluting monophenolic compounds in vegetation waters except through time-consuming and expensive separation processes. For these reasons, vegetation waters are currently treated as waste and are discarded without realizing their content of oleuropein.